1. Field of the Invention
The present invention relates to apparatus for controlling axial movement of a rotating member, and specifically to a feed attachment for controlling and limiting the axial movement of a rotatable boring bar relative to a workpiece.
2. Description of the Prior Art
In many operations, it is necessary to very carefully control the axial movement of a rotatable boring bar relative to a workpiece. For example, the annular sides of the supports for cam shaft bearings on an engine block need to be precisely machined or faced. Such machining is typically done with a boring machine. The engine block is mounted on the boring machine and a rotatable boring bar is extended through the cam shaft bearing openings on the engine block. The necessary facing or boring tools are mounted on the boring bar to be rotated and engage the workpiece for facing or boring adjacent the openings. One such boring machine is Model CB-2400, manufactured by the Tobin-Arp Manufacturing Company of Eden Prairie, Minn. Machines such as this Tobin-Arp machine can simultaneously face or bore a number of openings in a workpiece which are axially aligned.
There have been numerous attempts in the prior art to precisely control the axial movement of a rotatable tool bar relative to a workpiece. Examples of such devices are shown in the following U.S. Patents:
______________________________________ U.S. Pat. No. Patentee Issue Date ______________________________________ 1,882,689 Albertson 10/18/32 2,632,363 Boyce et al. 03/24/53 2,905,030 Cogsdill 09/22/59 ______________________________________
The device of the Albertson patent is a valve seat boring tool which uses a hand operated depth control for the cutter. This depth control is merely a manually threaded feed that limits the amount of penetration of the cutter being used. The device of the Boyce et al. patent is an apparatus for installing valve seats. The extent of axial movement of this device is limited by a ring which is threadably mounted on the device and which engages a stationary portion of the device when the device is moved to install a valve seat. The device of the Cogsdill patent is a countersink drive device which has a micrometer type of arrangement for presetting the depth of the countersink in the workpiece. The depth control and limiting arrangements of these three patents, which are typical of the prior art, are dissimilar from structure and function from the feed attachment of the present invention. These devices are not designed for use where multiple surfaces are to be simultaneously worked, and are not suitable for use in a boring machine environment.
U.S. Pat. No. 1,848,725, granted to Johnson on Mar. 18, 1932 and U.S. Pat. No. 3,767,316, granted to Dumont, Jr. on Oct. 23, 1973, both show boring machine arrangements wherein a plurality of tools are fixed to a rotatable boring bar for simultaneously working several surfaces of the workpiece. Neither patent, however, shows or discloses an arrangement for controlling the axial movement of the rotatable boring bar relative to the workpiece by placing the feed attachment directly on a portion of the workpiece and aligned with the workpiece for controlling the axial movement of the rotatable boring bar relative to the workpiece.
The feed attachment of the present invention contacts a portion of the workpiece and clamps directly to the boring bar and is alignable with respect to the workpiece surface to be worked to attain greater precision in controlling the axial movement of the boring bar. In addition, the present invention is easily adjustable and is positioned conveniently for use adjacent the workpiece on the boring bar.